Saturated internal instabilities in advanced-tokamak plasmas
Imperial College - Prince Consort Road, London SW7 2BY, UK
2 EURATOM/CCFE Fusion Association - Culham Science Centre, Abingdon, Oxfordshire OX14 3DB, UK, EU
Corresponding author: email@example.com
Accepted: 7 June 2010
“Advanced tokamak” (AT) scenarios were developed with the aim of reaching steady-state operation in future potential tokamak fusion power plants. AT scenarios exhibit non-monotonic to flat safety factor profiles (q, a measure of the magnetic field line pitch), with the minimum q (qmin) slightly above an integer value (qs). However, it has been predicted that these q profiles are unstable to ideal magnetohydrodynamic instabilities as qmin approaches qs. These ideal instabilities, observed and diagnosed as such for the first time in MAST plasmas with AT-like q profiles, have far-reaching consequences like confinement degradation, flattening of the toroidal core rotation or enhanced fast ion losses. These observations motivate the stability analysis of advanced-tokamak plasmas, with a view to provide guidance for stability thresholds in AT scenarios. Additionally, the measured rotation damping is compared to the self-consistently calculated predictions from neoclassical toroidal viscosity theory.
PACS: 52.55.Fa – Tokamaks, spherical tokamaks / 52.35.Py – Macroinstabilities (hydromagnetic, e.g., kink, fire-hose, mirror, ballooning, tearing, trapped-particle, flute, Rayleigh-Taylor, etc.)
© EPLA, 2010